1. Field of the Invention
The present invention relates generally to a prosthetic foot with an adjustable ankle. More particularly, the present invention relates to a prosthetic foot that simultaneously pivots downward and displaces forward.
2. Related Art
Many individuals have lost a limb for various reasons including war, accident, or disease. In most instances these individuals are not only able to live relatively normal lives, but physically active lives as well. Oftentimes, these individuals are aided in their everyday lives by a prosthetic limb. The objective of prosthesis is to provide an artificial limb that simulates the function and natural feel of the replaced limb.
With respect to prosthetic feet, the development of a functional and natural artificial foot has been limited only by material and imagination. Many designs have attempted to copy the anatomy of the foot or simulate its actions by replacing the bones and muscle with various mechanical components. Other designs have departed radically from mere anatomical copying or mechanical simulation by replacing the entire foot with an energy storage element such as a spring. As the user steps onto the foot, the user's weight compresses the spring. As the user moves forward, the user's weight comes off the foot and the energy stored in the spring is used to propel the user forward.
Almost all of the past designs have focused on the major aspect of the prosthetic foot—movement of the ankle or foot as it relates to walking or running. Few designs consider the use of the foot with different shoes, such as different heel heights. For example, some shoes, such as sneakers, have a generally level or horizontally flat platform, while other shoes, such as high-heels or boots, have a heel that is relatively elevated with respect to the toe. It will be appreciated that the ankle of a natural foot pivots to accommodate different heels. In a natural foot, the foot and toes rotate to conform to the slope of the terrain. The artificial foot of previous designs usually incorporates a unitary foot that is incapable of such movement at the ankle.
Some artificial feet have a dynamic pivot or hinge at the ankle, or a dynamic ankle joint. See U.S. Pat. Nos. 4,442,554; 5,482,513 and 5,913,902. During use, a foot member often pivots or swings up and down about a pivot or axle.
Some artificial feet have an adjustable ankle with a swivel connection, or a foot that pivots at the ankle. For example, see U.S. Pat. Nos. 5,800,564 and 6,402,790. Such feet often have a foot member that selectively pivots about a pivot.
Other feet have a foot member that adjusts linearly back and forth. For example, see U.S. Pat. No. 6,228,124.
One problem with some of the above configurations is that they have proved unsatisfactory in use with different types of shoes, such as shoes with different heel heights. Another problem with some of the above configurations is that they are complicated or difficult to adjust.